Characterization of phosphorus sorption on the sediments of Yangtze River Estuary and its adjacent areas   总被引：1，自引：0，他引：1  

Xiaoyan Cao  Xiaoyue Liu  Jiamei Zhu  Lisha Wang  Sumei Liu  Guipeng Yang 《Marine pollution bulletin》2017,114(1):277-284

This paper studied the kinetics, isotherm and thermodynamics of phosphorus sorption onto the sediments of the Yangtze River estuary and its adjacent waters, as well as the sediments' compositions and physicochemical properties. The process could be described well by a two-compartment first order equation. The sorbed phosphorus mainly consisted of Ex-P and Fe-P, with Ex-P being the dominant. The equilibrium isotherms could be fitted well with a modified Langmuir equation. The calculations of the thermodynamic parameters indicated that the process was spontaneous and exothermic. The CEC and the fractions of clay, calcite and organic matter were correlated with the sorption parameters, while the surface proton charge of the sediments was significantly negatively correlated with them. Considering the kinetics and phosphorus forms changes during the process, the sorption in our study could be considered that the physical process plays an important role.  相似文献   

Seasonal δ13CDIC sourcing and geochemical flux in telogenetic epikarst of south-central Kentucky     

Leah Jackson  Jason S. Polk 《地球表面变化过程与地形》2020,45(4):785-799

Telogenetic epikarst carbon sourcing and transport processes and their associated hydrogeochemical responses are complex and dynamic. Carbon dioxide (CO₂) transport rates in the epikarst zone are often driven by hydrogeochemical responses, which influence carbonate dissolution and conduit formation. This study examines the influence of land use on carbon sourcing and carbonate dissolution kinetics through a comparative analysis of separate, but similar, epikarst systems in south-central Kentucky. The use of high-resolution hydrogeochemical data from multiple data loggers and isotope analysis from collected water samples reflects the processes within these epikarst aquifers, which are estimated to contribute significantly to bedrock dissolution. Results indicate that, in an agricultural setting, long-term variability and dissolution is governed by seasonal production of CO₂ . In a more urbanized, shallower epikarst system, land cover may affect CO₂ transport between the soil and underlying bedrock. This concentration of CO₂ potentially contributes to ongoing dissolution and conduit development, irrespective of seasonality. The observed responses in telogenetic epikarst systems seem to be more similar to eogenetic settings, which is suggested to be driven by CO₂ transport occurring independent of high matrix porosity. The results of this study indicate site-specific responses with respect to both geochemical and δ¹³C_DIC changes on a seasonal scale, despite regional geologic similarities. The results indicate that further comparative analyses between rural and urban landscapes in other karst settings is needed to delineate the impact of land use and seasonality on dissolution and carbon sourcing during karst formation processes. © 2019 John Wiley & Sons, Ltd.  相似文献   

海水中大分子有机质对铂族元素的吸附动力学研究     

刘凯  高学鲁  邢前国  陈夫山 《海洋学报(英文版)》2019,38(8):8-16

Adsorption kinetics of the interaction between Pt, Pd and Rh(defined here as platinum group elements, PGEs)ions and macromolecular organic compounds(MOCs, 10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter(1 kDa and 3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and 1 kDa cutoff, and between Pd and humic acid.For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient(log_(10)K_d) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter(NDOM), an obvious difference in the change trends of log_(10)K_d and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log_(10)K_d of PGEs in the 1 kDa NDOM fraction were higher and more stable than those in the 3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research.  相似文献   

Phase stability and kinetics of methane hydrate formation in presence of calcium and magnesium carbonate     

Ekta Chaturvedi  Krishan Patidar  Sukumar Laik 《Marine Georesources & Geotechnology》2019,37(1):57-66

The huge amount of methane hydrate deposits identified in deep marine sediments is considered as the new resource for future energy. Since carbonates are one of the major components of marine sediments, in the present study, an investigation has been made to study methane hydrate stability and kinetics in the presence of CaCO₃ and MgCO₃. Effect of the presence of carbonates on the solubility of methane in the system has also been examined as it directly affects the hydrate formation process. It has been observed that in presence of CaCO₃ and MgCO₃, the hydrate formation is inhibited. Comparative studies have also been done in the presence of artificial seawater to consider the effect of presence of different salts. Mole consumption of methane gas during hydrate formation in different carbonate samples was measured using real gas equation and found to be minimum in CaCO₃ in seawater sample due to the combined effect of the presence of CaCO₃ and different salts of seawater. An increase in nucleation and induction time was also observed demonstrating the inhibition of hydrate formation in the presence of these components. Further, the decrease in hydrate formation rate also confirmed the inhibition effect of CaCO₃ and MgCO₃ on hydrate formation.  相似文献   

Sorption Preconcentration and Determination of Cobalt in Industrial Solutions by Diffuse Reflection Spectroscopy Method     

O. P. Kalyakina  O. N. Kononova  S. V. Kachin  A. G. Kholmogorov 《洁净——土壤、空气、水》2000,28(5):272-276

Cobalt and its compounds have a broad field of application in Russian industries, being essential raw materials for metallurgy, medicine, and agriculture. That is why the production of cobalt is one of the key industries in Russia. Cobalt is produced from mineral raw materials as well as from secondary raw materials (for example, after processing of spent catalysts of oil refinery). It can also be obtained as a by‐product of nickel, manganese, and some other metals processing. That is the reason why the solutions of Ni and Mn industries contain up to 50 g/L of cobalt. obalt compounds are harmful for men’s heart, bloodvessel system, and thyroid gland. This fact explains the importance of the monitoring of cobalt concentrations in natural water and sewages. This task can be effectively achieved using the analytical sorption technique. The present work is focused on the preconcentration of cobalt and its determination by means of diffuse reflection spectroscopy. The preconcentration of cobalt was carried out using the macronetwork cation exchangers KB‐2M and KB‐2‐3T synthesized on the basis of methyl acrylate and long‐chain cross‐linking agents copolymers. Based on these collectors, a cobalt determination method in industrial solutions was worked out using solid‐phase spectroscopy. The colored surface compound to be determined was obtained by a preceding cobalt sorption on the resin and by subsequent treatment of the concentrate obtained with definite amount of nitroso‐R‐salt. The Co calibration curve is linear in the concentration range of 0.05...0.50 mg/L Co (sample volume is 50.0 mL) and the detection limit is 0.02 mg/L (1 μg absolute).  相似文献   

花岗岩酸岩作用反应动力学研究     

岳高凡  李晓媛  甘浩男  王贵玲 《地质学报》2020,94(7):2107-2114

化学刺激能够改善增强型地热系统(EGS)热储层裂隙连通情况、提高裂隙渗透率。本文以EGS热储化学刺激为出发点,开展土酸体系 花岗岩作用实验,总结实验规律,明确了酸岩作用机理,建立多矿物耦合反应动力学模型并获取重要参数。得出以下结论：土酸中HF浓度越高,对花岗岩的溶蚀率和溶蚀速率就越大,但更易产生二次沉淀;酸液中离子的浓度与不同矿物溶蚀存在对应关系,Na+和K+分别来自于钠长石和伊利石,Al3+和硅来自长石类和黏土类矿物,Ca2+前期来自方解石,后期受钙长石和氟石影响;土酸 花岗岩反应为双重机制控制下的动力学反应;HF机制下的矿物溶解反应速率常数数量级约为10-4～10-5,比中性机制下的矿物的溶解速率提高了约9个数量级。研究结果可以为EGS储层化学刺激工作提供理论支持。  相似文献   

塔中地区奥陶系海相碳酸盐岩储层的溶解动力学特征     

张天付  崔振昂  钱一雄  谢淑云  鲍征宇 《地质科技情报》2007,26(3):19-25

选取塔中地区奥陶系海相碳酸盐岩样品进行了模拟实验,以研究其在表生岩溶作用下的溶解动力学特征.实验分别在30,50℃下,用pH值为3～6的盐酸溶液,恒温水浴加热进行.结果表明:4种样品溶解速率的相对大小依次为:灰白色灰岩＞砂屑灰岩＞粗晶白云岩＞中粗-细晶白云岩,且溶解速率均随着温度的升高而增大,随着pH值的增大而减小.但随着外界环境的变化,溶解速率的变化略有差异.造成这种差异的原因可能是样品中的硅酸盐杂质、晶体颗粒的大小以及实验过程中产生的CO2的影响.由实验结果推测可知,对于塔中地区以表生岩溶作用为主形成的奥陶系海相碳酸盐岩储层,灰岩储层的储集性能可能优于白云岩储层;对于以埋藏岩溶作用为主形成的奥陶系海相碳酸盐岩储层,白云岩储层的储集性能可能优于灰岩储层.  相似文献   

坡缕石对直接耐酸大红4BS的吸附动力学特征   总被引：3，自引：0，他引：3  

彭书传  崔康平  王诗生  陈天虎  姜绍通 《矿物学报》2006,26(3):267-271

研究了坡缕石对水中直接耐酸大红4BS的吸附动力学,在初始质量浓度为30~50 mg/L,转速为100~200 r/min,以及温度为303~348 K的范围内,坡缕石对直接耐酸大红4BS的吸附动力学数据均符合准二级速率方程。结果表明,坡缕石对直接耐酸大红4BS的吸附是外表面吸附,吸附表观活化能为11.92 kJ/mol,说明此吸附是由液膜扩散控制的物理吸附过程。  相似文献   

氧化铁矿物催化分解苯酚的动力学速率及其产物特征   总被引：3，自引：0，他引：3  

吴大清  刁桂仪  袁鹏 《矿物岩石地球化学通报》2006,25(4):293-298

本文研究了针铁矿、纤铁矿、赤铁矿和磁铁矿在过氧化氢参与下催化分解苯酚的动力学速率与溶液pH值的关系,并用紫外吸收谱测定了反应产物的谱学特征。结果表明,纤铁矿反应体系催化分解苯酚的速率常数(k)最大,其余依次为磁铁矿、针铁矿和赤铁矿。在纤铁矿反应体系中又以pH=3.8时反应速率常数最大。除赤铁矿反应体系外,当溶液pH=3~4时苯酚被完全分解,并有50%~65%的有机碳(TOC)被矿化。在pH=3.25的赤铁矿反应体系中,苯酚大多仅被转化为多酚,小部分苯环被打开形成己烯酸。当溶液pH=4~5时,苯酚一般仅被转化为多酚类化合物,但TOC基本不变。当溶液pH>5时,苯酚没有发生明显的转化和矿化现象。  相似文献   

沉积盆地超压系统内油气的生成与保存   总被引：1，自引：0，他引：1  

肖七林  孙永革 《地球化学》2007,36(4):375-382

沉积盆地内的超压系统是一个相对独立的封闭-半封闭体系,与油气生成、保存关系密切.超压系统内矿物介质、有机质、水相互作用过程以及有效应力对有机质演化的作用机理研究揭示了超压对有机质演化具有显著的阶段性和差异性,具体表现在:(1)压力的影响程度是有机质演化程度的函数;(2)超压/压力效应对有机质演化发生显著影响需要达到某一最小值,即门限值;(3)在有机质演化不同阶段发育的超压对生烃的影响不同;(4)同一超压系统内,不同类型有机质对超压的响应具有差异性.迄今,已经建立了超压/压力对有机质演化影响程度的定量化模型,包括化学动力学模型和热力学模型两类.化学动力学模型仍有许多需要改进的地方,如压力影响的阀值、指前因子和活化能随反应时间的变化规律等,相对而言,热力学模型似乎更简单、易用,但其可靠性和普适性还有待时间的检验.由于异常高压对超压系统储层内原油的热裂解反应具有抑制效应,有利于深部高温高压储层内液态烃的保存,因此,含油气盆地深部高温高压地层已成为一个较为有利的石油勘探领域.  相似文献